Hyodo Kazutaka is a major antagonist in the Kaiji series, serving as the powerful and tyrannical president of the Teiai Corporation, a financial consulting firm that also operates a vast underground gambling empire. Believed to be around seventy years old and worth several hundred billion yen, he has been driven mad by his immense wealth. Conventional hobbies fail to provide him any satisfaction, so he sponsors and hosts deadly gambling tournaments for the sole purpose of watching desperate people struggle against terror and despair. Hyodo displays a profoundly cruel and sadistic personality, holding a deep contempt for the lower class, whom he refers to as scum. He believes poverty is an inescapable paradox, stating that the poor desire money in the hopes of becoming king themselves, which in turn only strengthens the position of the current king, himself. Maintaining absolute power is his core philosophy, and he has even invested in constructing an underground bunker to preserve his wealth and status in case of societal collapse.

As the sponsor of the games that protagonist Kaiji Ito is forced into, Hyodo becomes his ultimate nemesis. He is present at the climax of the first major gamble and later meets Kaiji in person for a final contest in the first story arc. This gamble, known as the Tissue Box Raffle, showcases Hyodo's cunning nature. He outsmarts Kaiji by subtly folding the winning lottery ticket, creating a small crease that allows him to easily locate it when it is his turn to draw, resulting in Kaiji losing four fingers on his left hand. Hyodo also oversees Kaiji’s challenges from a distance, such as during the Bog gamble, where he contacts the casino owner to threaten dire consequences if Kaiji should win.

Hyodo's relationships are defined by his absolute authority and lack of empathy, including toward his own family. His subordinates, such as his right-hand man Yukio Tonegawa, live in constant fear of his unpredictable and humiliating demands. He forces employees to act as footstools or to drink wine that he has contaminated with his feet. After Tonegawa is defeated by Kaiji, Hyodo is disgusted not by the loss itself but by his subordinate’s failure, forcing him to kneel in apology on a scorching hot iron plate as a form of entertainment. In his family life, he is a neglectful father who openly favors his eldest son, Kazuki, over his younger son, Kazuya, reprimanding both for things beyond their control. He is also a widower, as his wife Sophie passed away prior to the events of the series.

Throughout the series, Hyodo undergoes little personal change, remaining a static symbol of corrupt and absolute power. However, his development is seen in the reactions he provokes in others, particularly reinforcing Kaiji’s determination to defeat him. While Hyodo is consistently portrayed as an insurmountable figure of cruelty, a rare glimpse of uncharacteristic behavior is shown in a flashback where he expresses concern over a child’s toy being too violent, hinting at a more reserved personality in his distant past. His motivations are unchanging: he is entertained only by the extreme anguish of others and is driven by a desire to maintain his position as a king of wealth. When his son Kazuya later falls into a coma following a gambling defeat, Hyodo’s grief manifests not as compassion but as cold, furious rage, as he orders a manhunt and nearly forces an underling to commit suicide. Hyodo's notable abilities are not magical or physical but cerebral. He possesses a genius-level intellect for strategy and cheating, a complete lack of morality that allows him to act without hesitation, and the overwhelming power afforded by his vast fortune, which allows him to manipulate lives and fates on a massive scale.